The committee will say on Friday it "did not receive the reassurances it wanted" about the role of HIW, which inspects and regulates healthcare.

It found a lack of clarity had "undermined its ability to establish itself as an authoritative regulator".

In its evidence to the committee, HIW said it could not give "strong assurances" that a situation like the Mid Staffordshire hospital scandal is not happening in the Welsh NHS.

The Francis report in February 2013 highlighted the "appalling and unnecessary suffering of hundreds of people" at Stafford Hospital which may have contributed to subsequent deaths.

'Fit for purpose'

The review should be undertaken as a matter of urgency and should result in a clear outline of HIW's objectives and core purposeReport of the Health and Social Care Committee

HIW told the committee of AMs that staffing issues meant it could not deliver "sufficient coverage" in terms of tests.

Health Minister Mark Drakeford told the same inquiry he previously had concerns about HIW's capacity but had been reassured by a review undertaken by the new chief executive into the inspectorate's functions.

HIW, although part of the Welsh government, is the operationally independent inspectorate and regulator of all healthcare in Wales.

The Health and Social Care Committee undertook the short inquiry to satisfy itself that HIW was "fit for purpose".

But in the key conclusion to the inquiry report seen by BBC Wales, the committee says "it did not receive the reassurances it wanted to hear about the role of HIW in ensuring that healthcare providers are examined properly, meet basic standards, and face sufficient intervention when basic standards are not met".

It added: "Furthermore, the committee did not receive reassurances that the purpose and role of HIW has been defined sufficiently to provide a clear, robust and understood inspection and regulatory regime.

"It is our view that this lack of clarity has undermined HIW's ability to establish itself as an authoritative regulator."

'Develop and improve'

The report adds that no "serious issues relating to quality and safety of services" were identified during the inquiry but neither was the committee reassured that "should such issues arise in the Welsh NHS, they would be detected in a timely or systematic way if we were to rely upon HIW alone".

As a result, the committee will make just one key recommendation, "that the Welsh government should undertake a fundamental review of HIW to reform, develop and improve its regulatory and inspection functions".

It added: "Consideration of the need to reform HIW's statutory foundation should form part of this review, as should the key issues raised in this report.

"The review should be undertaken as a matter of urgency and should result in a clear outline of HIW's objectives and core purpose."